1. Field of the Invention
This invention generally relates to a solenoid actuator using an electromagnetic power generated between a coil and a magnet.
2. Description of the Related Art
Generally, a solenoid generates a mechanical linear motion of a movable core inserted in a coil with magnetic power when a given voltage is applied to the coil. Japanese Patent Application Publications No. 2003-306149 and No. 2004-296129 disclose a solenoid using a permanent magnet instead of the movable core.
It is possible to further increase the thrust force of the solenoid mentioned above, when the current given to the coil is enhanced. The current which can be given to the coil is limited actually. On the other hand, the solenoid needs an optical encoder or the like in order to detect a position of a movable object. And the device grows in size and the cost is increased.